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Re: Re: More Holtz on the origin of birds



>In a message dated 95-12-07 12:10:26 EST, Thomas_R_HOLTZ@umail.umd.edu (th81)
>writes:
>
>>Dromaeosaurids, therizinosauroids, and birds are all theropods with a
>>retroverted pubis.  This is associated with the decoupling of the tail from
>>locomotory use (the tail is a vital part of locomotion in most diapsids).
>>
>>
>
>Probably not in segnosaurs (=therizinosauroids). As herbivores (and
>prosauropod and ornithischian relatives, not theropods), they got their
>opisthopubic pelvis the old-fashioned way: to make room for their gut. It's
>probably why the pelvis was so splayed out anteriorly, too.


Which I agree with later in my comments, but fair enough.  It would have
modified the locomotory apparatus, anyway, but no one has suggest fleet
flocks of therizinosaurs dashing across ancient Mongolia... :-)

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084